The present invention relates to instruments and methods for connecting body tissues, or body tissue to prostheses.
Minimally invasive surgery has allowed physicians to carry out many surgical procedures with less pain and disability than conventional, open surgery. In performing minimally invasive surgery, the surgeon makes a number of small incisions through the body wall to obtain access to the tissues requiring treatment. Typically, a trocar, which is a pointed, piercing device, is delivered into the body with a cannula. After the trocar pierces the abdominal or thoracic wall, it is removed and the cannula is left with one end in the body cavity, where the operation is to take place, and the other end opening to the outside. A cannula has a small inside diameter, typically 5-10 millimeters, and sometimes up to as much as 20 millimeters. A number of such cannulas are inserted for any given operation.
A viewing instrument, typically including a miniature video camera, or optical telescope is inserted through one of these cannulas and a variety of surgical instruments and refractors are inserted through others. The image provided by the viewing device may be displayed on a video screen or television monitor, affording the surgeon enhanced visual control over the instruments. Because a commonly used viewing instrument is called an xe2x80x9cendoscope,xe2x80x9d this type of surgery is often referred to as xe2x80x9cendoscopic surgery.xe2x80x9d In the abdomen, endoscopic procedures are commonly referred to as laparoscopic surgery, and in the chest, as thoracoscopic surgery. Abdominal procedures may take place either inside the abdominal cavity (in the intraperitoneal space) or in a space created behind the abdominal cavity (in the retroperitoneal space). The retroperitoneal space is particularly useful for operations on the aorta and spine or abdominal wall hernia.
Minimally invasive surgery has virtually replaced open surgical techniques for operations such as cholecystectomy and anti-reflux surgery of the esophagus and stomach. This has not occurred in either peripheral vascular surgery or cardiovascular surgery. An important type of vascular surgery is to replace or bypass a diseased, occluded or injured artery. Arterial replacement or bypass grafting has been performed for many years using open surgical techniques and a variety of prosthetic grafts. These grafts are manufactured as fabrics (often from DACRON(copyright) (polyester fibers) or TEFLON(copyright) (fluorocarbon fibers)) or are prepared as autografts (from the patient""s own tissues) or heterografts (from the tissues of animals) or a combination of tissues, semi-synthetic tissues and or alloplastic materials. A graft can be joined to the involved artery in a number of different positions, including end-to-end, end-to-side, and side-to-side. This attachment between artery and graft is known as an anastomosis. Constructing an arterial anastomosis is technically challenging for a surgeon in open surgical procedures, and is almost a technical impossibility using minimally invasive techniques.
Many factors contribute to the difficulty of performing arterial replacement or bypass grafting. See generally, Wylie, Edwin J. et al., Manual of Vascular Surgery, (Springer-Verlag New York), 1980. One such factor is that the tissues to be joined must be precisely aligned with respect to each other to ensure the integrity and patency of the anastomosis. If one of the tissues is affixed too close to its edge, the suture can rip through the tissue and impair both the tissue and the anastomosis. Another factor is that, even after the tissues are properly aligned, it is difficult and time consuming to pass the needle through the tissues, form the knot in the suture material, and ensure that the suture material does not become tangled. These difficulties are exacerbated by the small size of the artery and graft. The arteries subject to peripheral vascular and cardiovascular surgery typically range in diameter from several millimeters to several centimeters. A graft is typically about the same size as the artery to which it is being attached. Another factor contributing to the difficulty of such procedures is the limited time available to complete the procedure. The time the surgeon has to complete an arterial replacement or bypass graft is limited because there is no blood flowing through the artery while the procedure is being done. If blood flow is not promptly restored, sometimes in as little as thirty minutes, the tissue the artery supplies may experience significant damage, or even death (tissue necrosis). In addition, arterial replacement or bypass grafting is made more difficult by the need to accurately place and space many sutures to achieve a permanent hemostatic seal. Precise placement and spacing of sutures is also required to achieve an anastomosis with long-term patency.
Highly trained and experienced surgeons are able to perform arterial replacement and bypass grafting in open surgery using conventional sutures and suturing techniques. A suture has a suture needle that is attached or xe2x80x9cswedged onxe2x80x9d to a long, trailing suture material. The needle must be precisely controlled and accurately placed through both graft and artery. The trailing suture material must be held with proper tension to keep the graft and artery together, and must be carefully manipulated to prevent the suture material from tangling. In open surgery, these maneuvers can usually be accomplished within the necessary time frame, thus avoiding the subsequent tissue damage (or tissue death) that can result from prolonged occlusion of arterial blood flow.
The difficulty of suturing a graft to an artery using minimally invasive surgical techniques has effectively prevented the safe use of this technology in both peripheral vascular and cardiovascular surgical procedures. When a minimally invasive procedure is done in the abdominal cavity, the retroperitoneal space, or chest, the space in which the operation is performed is more limited, and the exposure to the involved organs is more restricted, than with open surgery. Moreover, in a minimally invasive procedure, the instruments used to assist with the operation are passed into the surgical field through cannulas. When manipulating instruments through cannulas, it is extremely difficult to position tissues in their proper alignment with respect to each other, pass a needle through the tissues, form a knot in the suture material once the tissues are aligned, and prevent the suture material from becoming tangled. Therefore, although there have been isolated reports of vascular anastomoses being formed by minimally invasive surgery, no system has been provided for wide-spread surgical use which would allow such procedures to be performed safely within the prescribed time limits.
As explained above, anastomoses are commonly formed in open surgery by suturing together the tissues to be joined. However, one known system for applying a clip around tissues to be joined in an anastomosis is disclosed in a brochure entitled, xe2x80x9cVCS Clip Applier Systemxe2x80x9d, published in 1995 by Auto Suture Company, a Division of U.S. Surgical Corporation. A clip is applied by applying an instrument about the tissue in a nonpenetrating manner, i.e., the clip does not penetrate through the tissues, but rather is clamped down around the tissues. As previously explained, it is imperative in forming an anastomosis that tissues to be joined are properly aligned with respect to each other. The disclosed VCS clip applier has no means for positioning tissues. Before the clip can be applied, the tissues must first be properly positioned with respect to each other, for example by skewering the tissues with a needle as discussed above in common suturing techniques or with forceps to bring the tissues together. It is extremely difficult to perform such positioning techniques in minimally invasive procedures.
Therefore, there is currently a need for other tissue connector assemblies.
The present invention involves improvements to devices for connecting tissues or tissue(s) and grafts, such as in a vascular anastomosis. The invention generally involves a surgical fastener which has an end portion that is releasably coupled to a plurality of strands that function as a release mechanism. One advantage of this release mechanism is that a needle or other piercing or penetrating member may be coupled to it to thereby releasably couple the needle, piercing member or penetrating member to the fastener.
Preferably, the surgical fastener comprises a shape memory material, most preferably nitinol. Preferably, the fastener comprises a wire. The wire may be a tubular wire. The wire preferably has a generally circular cross-section.
According to one aspect of the invention, a tissue connector assembly is provided with a clip movable between an open configuration and a closed configuration, and a mechanical restraining device coupled to the clip for restraining the clip in the open configuration. The mechanical restraining device includes a release mechanism having a plurality of strands which may be releasably coupled to an enlarged portion of the clip.
The mechanical restraining device may include a coil surrounding at least a portion of the clip. The mechanical restraining device may further include a clip retainer fixed at an end portion of the clip opposite the enlarged end portion. Preferably, the clip retainer has a cross-sectional area greater than a cross-sectional area of the coil.
The coil includes a plurality of adjacent loops and is compressible with the plurality of adjacent loops being spaced closer to one another along one side of the coil than along an opposite side of the coil. Coupling of the release mechanism to the enlarged portion compresses the coil between the release mechanism and the retainer clip thereby biasing the clip in the open position.
The strands of the release mechanism may comprise substantially rigid wires. Alternatively, the strands may comprise substantially rigid cables. Each strand may include a notch for receiving part of the enlarged portion of the clip during releasable engagement.
The clip may have a generally U-shaped configuration when in the open configuration. A needle may be releasably attached to the clip to facilitate removal of the needle after insertion of the clip through the tissues/grafts. At least a portion of the mechanical restraining device may remain on the clip when the needle is released from the clip.
According to another aspect of the invention, the release mechanism of the tissue assembly may include a plurality of strands arranged in a circle and substantially parallel to one another to form a tube-like configuration, with proximal end portions of the strands being coupled to a needle. Alternatively, the proximal end portions may be coupled to a transition element which is connected to a needle by a flexible element, preferably a suture.
The distal end portions of the strands may include notches configured to receive and lock the enlarged portion of the clip within a chamber defined by the notches. A shrink wrap layer may be provided to surround at least the distal end portions of the strands, and is heat shrunk against the strands to compress the notches against the enlarged portion of the clip to more securely retain the enlarged portion. The shrink wrap layer may be a shrink tubing.
Compression of the plurality of strands in a location between the notches and the coupled proximal end portions, deforms the chamber to enable removal of the enlarged portion from the chamber. Removal of the enlarge portion from the chamber initiates closing of the clip. The clip is in a relaxed state when in the closed configuration. The clip may assume a spiral configuration in the closed configuration.
The above is a brief description of some deficiencies in the prior art and advantages of the present invention. Other features, advantages, and embodiments of the invention will be apparent to those skilled in the art from the following description, accompanying drawings, and claims.